Delirium in Parkinson’s disease patients. A five-year follow-up study

Marcos Serrano-Duenasa,b,*, Marıa J. Bledac,d

aAbnormal Movement Disorders Unit, Neurological Service, Hospital Carlos Andrade MarınbFacultad de Medicina, Pontificia Universidad Catolica del Ecuador, P.O. Box: 17-03-1694, Quito - Ecuador

cNational Center of Epidemiology, Carlos III Research Institute, Madrid - SpaindDepartment of Statistics, Universidad Carlos III de Madrid

Received 23 July 2004; revised 10 May 2005; accepted 11 May 2005

Abstract

Objective: To assess the significance of delirium in parkinsonian patients in a 5-year follow-up case-control study with three groups of

patients: Parkinsonian and Delirium (PDG), Parkinsonian (PG) and Control (CG). Methods: Comparisons of Short Test of Mental Status

(STMS) and Unified Parkinson’s Disease Rating Scale-motor section (UPDRS(m)) between groups were performed using analysis of

variance with repeated measurements. Comparisons of survival functions and Cox regression models were used to analyse the time until

death. Results: STMS and UPDRS(m) mean scores were statistically different between PDG group and the other two groups (p!0.001) and

between PDG and PG groups (p!0.001), respectively. Including all groups, PG’s patients (HRZ0.29; 95% C.I.Z0.09–0.93) and CG’s

patients (HRZ0.13; 95% C.I.Z0.03–0.60) had less hazard to die than PDG’s patients; patients with a STMS basal score O33 (HRZ0.37;

95% C.I.Z0.13–0.99) had less hazard to die than patients with a score %33. Finally, including PDG and PG groups, patients with basal

UPDRS(m) score O17 (HRZ4.88; 95% C.I.Z1.11–21.48) had higher hazard to die than patients with a score %17. Conclusion: For patients

with Parkinson’s, delirium is an increased risk factor for developing dementia, to have a more severe motor impairment and to death.

q 2005 Elsevier Ltd. All rights reserved.

Keywords: Parkinson’s disease; Delirium; Survival analysis; Repeated measurements

1. Introduction

Delirium is an acute organic brain syndrome presenting

with whole cognitive impairment, attention disorders,

reduced level of consciousness, increased or decreased

psychomotor activity, and wake-sleep rhythm disorders [1–

5]. The prevalence of delirium is variable due to the

difference in population studied and distinct diagnostic

criteria used [5], but there is consensus that this increases

with aging [6], with rates as high as 60% reported in

hospitalised elderly patients [7].

On the other hand, Parkinson’s Disease (PD) mostly affects

older people [8], and risk for postoperative delirium varying

between 2.8 and 8.1 among patients with PD against controls

[9], and occurrence of delirium in 5–25% of Parkinson patients

treated with levodopa have been reported [10].

1353-8020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.parkreldis.2005.05.002

* Corresponding author.

E-mail address: serranom@pi.pro.ec (M. Serrano-Duenas).

The mesocortical dopaminergic system has been

involved in the physiopathology of delirium. This proposal

has been supported by the fact that neuroleptics are useful in

treating delirium [5], and additionally because dopamin-

ergic medications are known to be likely to cause delirium

[10], which determines the great complexity in handling

delirium in parkinsonian patients, in which neuroleptics

aggravate the disease [11].

While delirium has traditionally been considered as

temporary and reversible [12], recent evidence has

associated it with increased morbidity, mortality and as a

risk factor for developing dementia, i.e., it can lead to

catastrophic consequences [2,3,6].

This 5-year prospective comparison observational study

was conducted to identify behavior in patients with PD

developing delirium against a group of patients with PD and

a control group.

2. Patients, materials, and methods

A consecutive series of 21 patients with PD (recorded on

the Abnormal Movements Clinic, Neurology Service,

Parkinsonism and Related Disorders 11 (2005) 387–392

www.elsevier.com/locate/parkreldis

Table 1

Demographic and clinical patients’ characteristics by groups

Variables PDG (nZ21)

PG (nZ21) CG (nZ21) P

Age (years) 67.7 (5.3) 67.5 (5.4) 67.1 (5.9) 0.9a

STMS 34.5 (2.0) 34.7 (1.6) 34.4 (2.1) 0.9a

Gender (M/

F)

14/7 16/5 11/10 0.3b

Variables PDG (nZ21) PG (nZ21) p

Disease dur-

ation (years)

6.05 (1.4) 6.0 (1.5) 0.8a

UPDRS(m) 18.4 (2.8) 19.2 (2.6) 0.4a

H and Y (1.5/2) 11/10 13/8 0.5b

S and E (70/80/

90)

3/12/6 3/12/6 1b

Daily levodopa

(mg)

n (%) n (%)

500 5 (23.8%) 2 (9.5%)

625 11 (52.4%) 12 (57.1%)

750 5 (23.8%) 7 (33.3%) 0.4b

x(y), mean (standard deviation); x/y, absolute frequency of first class/

absolute frequency of second class.a Means comparison (ANOVA test); p!0.05 as significant.b Pearson chi-square test; p!0.05 as significant.

M. Serrano-Duenas, M.J. Bleda / Parkinsonism and Related Disorders 11 (2005) 387–392388

‘Carlos Andrade Marın’ Hospital, a third level reference

hospital) who met criteria for delirium according to the

Confusion Assessment Method of Inouye et al [7], (the

Confusion Assessment Method requires the presence of (i)

Acute onset and fluctuating course;(ii) Inattention; (iii)

Disorganized thinking; and (iv) Altered level of conscious-

ness. The diagnosis of delirium requires the presence of

features (i) and (ii) and either (iii) or (iv)).

The patients were assessed by one of the authors (MS-D),

between January 1994 until December 1999 and designated

as Parkinson and Delirium Group (PDG). Only those with a

previous assessment (up to 3 months before the occurrence

of delirium) of their higher mental functions (using the

Short Test of Mental Status STMS) [13] that ruled out

dementia were included; and an assessment of either the

presence or absence of depression using the Hamilton scale

[14] that excluded those with depression (the cut-off score

was 12/13). Those in which a previous evaluation (within

the last 3 months) of their parkinsonian condition through

the UPDRS motor section [15] was not available were

excluded as well.

Additionally, two control groups were used, one formed

by 21 patients with PD, called Parkinson Group (PG), and

the other one including 21 relatives (husbands or wives of

patients with PD), referred to as the control Group (CG).

Both patients in the PG and CG were excluded if they had,

as in the case above, a score of 28 or lower on the STMS or

scored with depression under the Hamilton scale (with a

similar cut-off score of 12/13). For patients in the PG, those

without an assessment within the last 3 months of the

UPDRS motor section were excluded. The general health

status in the PG, in the CG, and pre-delirium in the PDG,

was similar without severe disease.

Relevant demographic and clinic variables were collected

in all of them; the three groups had a total of 11 assessments:

the so-called Basal Evaluation (BE) and other 10 assess-

ments performed every 6 months. All assessments included

the STMS for the three groups, the UPDRS(m), Hoehn and

Yahr (H and Y) [16], Schwab and England Scale (SES) [17]

for those within the PDG and PG. The BE of the PDG was the

last recorded immediately before development of delirium.

The Analysis of variance (ANOVA) [18] was used to

compare age mean and STMS basal scores mean between

the 3 groups, and also to compare disease duration mean and

the UPDRS(m) mean between PDG and PG groups. The

Pearson chi-square test [19] was used to evaluate differences

of proportions by gender (between all groups) and, by H and

Y, SES and daily levodopa between PDG and PG groups. A

p-value lower than 0.05 was accepted as statistically

significant.

Comparison of the eleven assessments of STMS and

UPDRS(m) mean scores collected through the five years of

follow-up were performed using an ANOVA with repeated

measurements [20].

To analyse the time until death between groups we

compare these groups’ survival functions estimated by

the Kaplan-Meier method using the log-rank test [21]. We

also compared the three pairs of survival functions and then

we corrected the global-aZ0.05 for multiple comparisons

using Bonferroni’s method (aBonferroniZ0.017). Finally, to

identify which of these factors: gender, basal age, group,

basal STMS, years of illness, basal H and Y and basal

UPDRS(m) were related to the time until death, we

performed a first Cox regression model including the three

groups and a second Cox regression model including only

PDG and PG groups [21].

All statistical analysis were performed using Stata

8.0 [22].

3. Results

Delirium causes were: prostatectomy (benign hyperpla-

sia), 4 patients; hip surgery, 8 (5 men, 3 women);

dehydration, 3 (1 man, 2 women); pneumonia, 5 (3 men, 2

women); and finally, use of anti-flu medication (this patient

take 4 pill (each with 2,5 mg of loratadine, 60 mg of

pseudoefedrine and 500 mg od acetaminophen), 1 male

patient. Delirium was the agitated type in 16 patients; in 6

patients do not have altered level of sensorium.

There were no statistically significant differences on

mean age, on mean STMS basal scores and on gender

between the three groups. There were no differences

between PDG and PG groups on mean disease duration,

on mean UPDRS(m) basal score, on H and Y, on SES and

on daily doses of levodopa (Table 1).

Analysing variables collected during 5-year follow-up,

values were correlated. We performed an ANOVA with

M. Serrano-Duenas, M.J. Bleda / Parkinsonism and Related Disorders 11 (2005) 387–392 389

repeated measurements to analyse data. The first result was

a statistically significant decreasing trend in the STMS mean

score and the UPDRS(m) mean scores through time. Taking

this trend into account, there was a statistically significant

difference in STMS mean scores between the PDG group

and the other two groups (p!0.001); nevertheless, there

was no difference in STMS mean scores between PG and

CG groups (p0.769). Comparing UPDRS(m) mean scores

only between PDG and PG groups, there was also a

statistically significant difference (p!0.001) (Table 2).

Analysing the time until death, we estimated survival

functions using the Kaplan-Meier method. We compared

the three survival functions using the log-rank test which

showed a statistically significant difference between groups

(p!0.05). To identify which pairs of survival functions

were different, we performed three pairs of comparisons:

PDG versus PG, PDG versus CG and PG versus CG. There

were statistically significant differences only between

survival functions of PDG and CG groups (p!0.017)

(Fig. 1).

Table 2

Comparison of short test of mental status (SMTS) and unified Parkinson’s diseas

Groups BASALa 1 (6 m)b 2 (12 m) 3 (18 m) 4 (24 m) 5 (30 m

STMS

Parkin-

son’s and

delirium

(PDG)

34.5 (2.

0)c

31.8 (2.2) 31.0 (2.3) 29.8 (2.8) 27.4 (3.3) 26.3 (3.2

nZ21d nZ21 nZ21 nZ19 nZ18 nZ17

Parkin-

son’s

(PG)

34.7 (1.6) 34.4 (1.9) 34.1 (2.1) 33.8 (1.9) 33.3 (1.8) 32.6 (2.0

nZ21 nZ21 nZ21 nZ21 nZ21 nZ21

Control

(CG)

34.4 (2.1) 34.0 (2.0) 33.3 (2.2) 33.2 (2.3) 32.8 (2.3) 32.6 (2.5

nZ21 nZ21 nZ21 nZ21 nZ21 nZ21

Group differences

adjusting by repeated

measures

PDG versus PG PDG ve

P !0.001 !0.001

UPDRS(m)

Parkin-

son’s and

delirium

(PDG)

18.4 (2.

8)c

22.1 (2.8) 25.4 (2.7) 28.8 (2.9) 32.8 (3.0) 33.7 (3.1

nZ21d nZ21 nZ21 nZ21 nZ18 nZ17

Parkin-

son’s

(PG)

19.2 (2.6) 19.4 (2.5) 19.9 (2.2) 20.8 (2.0) 21.9 (1.8) 23.3 (1.9

nZ21 nZ21 nZ21 nZ21 nZ21 nZ21

Group

differ-

ences

adjusting

by

repeated

measures

p

a No significant differences between means at basal time (p O 0.10).b First assessment at 6 months.c Mean (standard deviation).d Number of subjects in this time.

To identify factors associated with the time until death,

we performed a Cox regression model including all cases

and controls (nZ63). The statistically significant factors in

the model were associated negatively, indicating higher

survival (less hazard to die) for: PG group (Hazard Ratio

(HR)Z0.29; 95% C.I.Z0.09–0.93) and CG group (HRZ0.13; 95% C.I.Z0.03–0.60) compared with PDG group;

patients with a STMS basal score O33 compared with

patients with a STMS basal score %33 (HRZ0.37; 95%

C.I.Z0.13–0.99) (Table 3).

We also performed a second Cox regression model

including only cases from PDG and PG groups (nZ42).

There were two factors associated negatively: PG (HRZ0.11; 95% C.I.Z0.03–0.41) compared with PDG and a

HY basal scoreZ2 compared to HY basal scoreZ1.5

(HRZ0.19; 95% I.C.Z0.05–0.70); and one factor

associated positively, indicating less survival (high

hazard to die): basal UPDRS(m) score O17 compared

to basal UPDRS(m) score %17 (HRZ4.88; 95% C.I.Z1.11–21.48) (Table 3).

e rating scale (motor section) (UPDRS(m)) by groups

) 6 (36 m) 7 (42 m) 8 (48 m) 9 (54 m) 10 (60 m) Trend

differ-

ences

) 25.4 (2.9) 24.4 (3.0) 22.9 (3.2) 21.6 (3.4) 21.1 (3.3) p!0.001

NZ15 nZ14 nZ13 nZ11 nZ11

) 32.6 (2.0) 32.3 (1.9) 32.0 (1.9) 31.8 (2.1) 31.6 (2.1) p!0.001

NZ21 nZ20 nZ20 nZ18 nZ17

) 32.4 (2.4) 32.3 (2.3) 32.1 (2.1) 32.0 (2.0) 32.1 (2.1) p!0.001

NZ21 nZ20 nZ20 nZ20 nZ19

rsus CG PG versus CG

Z0.769

) 35.3 (3.6) 38.2 (4.4) 40.2 (4.1) 41.8 (3.7) 44.5 (4.1) p!0.001

NZ15 nZ14 nZ13 nZ11 nZ11

) 24.9 (1.9) 26.2 (2.0) 27.6 (1.9) 28.7 (2.4) 30.3 (2.1) p!0.001

NZ20 nZ20 nZ20 nZ18 nZ17

PDG versus PG

!0.001

19

11

17

21 21 21

0.00

0.25

0.50

0.75

1.00

0 12 24 36 48 60Time analysis: months

PDG PGCG

Kaplan-Meier survival estimates by groups

pLog-rank test for equality of survivor functions 0.0045a

Comparisons PDG versus PD 0.031PDG versus CG 0.0046b

PG versus CG 0.38a p < 0.05 as significantb Applying Bonferroni correction, p < 0.017 as significant

Fig. 1. Estimated survival functions by groups.

M. Serrano-Duenas, M.J. Bleda / Parkinsonism and Related Disorders 11 (2005) 387–392390

Related to survival analysis, there were no differences of

survival functions by gender; the Cox’ regression model

showed that there were no evidences of a by gender effect.

At the end of follow-up, 10 deaths were recorded for the

PDG group, 4 deaths for the PG and 2 deaths for the CG.

Table 3

Time until death analysis

Variables

included

ALL GROUPS (nZ63) PDG and PG (nZ42)

Hazard

Ratio

(95% C.I.) Hazard

Ratio

(95% C.I.)

Gender

(Female)

0.85 (0.29–2.50) 0.26 (0.05–1.30)

Male

Basal age 1.02 (0.93–1.12) 1.11 (0.98–1.25)

Group

(PDG)

PG 0.29a (0.09–0.93) 0.11a (0.03–0.49)

CG 0.13a (0.03–0.60) –

Basal

STMS

(!Z33b)

0.37a (0.13–0.99) 0.56 (0.14–2.26)

O 33

Years of

disease

1.30 (0.84–2.03)

Basal Hand

Y (1.5)

0.19a (0.05–0.70)

H and YZ2

Basal

UPDRS(m)

(!Z17b)

4.88a (1.11–21.

48)

O17

Reference categories are in brackets. Results of Cox’s regression models.a p!0.05 as significant.b !Z25th percentile.

4. Discussion

This study confirms the outcomes from previous

publications where patients with increased risk for

developing delirium are shown to be: the elderly hospital-

ised patients [12], with a previous central nervous system

(CNS) disease [5], patients with Parkinson’s disease [9] and

those using antihistaminic medications [23]. Additionally,

and according to the vulnerability schema proposed by

Inouye et al. [24], the elderly and patients with a previous

CNS disease require less heavy noxas to develop delirium.

Furthermore, delirium becomes a risk factor for

developing dementia and death [6]. For patients in this

study (PDG), SMTS mean scores since the fourth evaluation

(corresponding to the 24 months) was 27.5 (scores below 29

are considered as dementia); likewise, a significant

difference in cognitive response is already found after the

first evaluation (at six months of the event), which increases

and persists over the remaining follow-up.

This study shows that PDG patients have a significant

trend for having their higher functions impaired as measured

by the STMS, compared with both PG and CG group

patients. The primary role of delirium is confirmed since no

differences were seen for this variable between the PG and

CG groups. Similarly, the damaging role of this acute

confusion syndrome is seen by comparing the UPDRS(m)

score between PDG and PG groups. Patients with delirium

had a significant impairment as compared with those that

did not develop this complication.

In comparing the survival curves for the three groups,

overall significant differences were found suggesting that

there were at least two different survival functions (PDG

and CG group functions). This implicate that Parkinson’s

disease per se has no mayor repercussions.

The Cox regression model, including all groups, showed

that a basal STMS rating between 33/38 scores significantly

increases the risk to die, whereas there was no influence

from gender or age. Let us remember that on the STMS a

score %29 implies dementia cognitive impairment. The

presence of predictors for developing psychotic disorders

(delirium has been assumed as part of this syndrome) [25,

26] has been shown in other studies. Cognitive impairment

[27] is among these recognized predictors; our findings are

in agreement with this recognition.

Likewise, cognitive impairment was been associated to

an increased mortality risk [28]. Accordingly, our PDG

patients showed increased development of cognitive

impairment and dementia (STMS score !29) as shown in

Table 2.

Relating to the development of dementia and death, our

patients with Parkinson’s disease were not different from

other elderly patients. In our opinion, the newest fact is

verifying that patients go through a significant impairment

of their motor function as measured by the UPDRS motor

section. From the second evaluation (corresponding to the

M. Serrano-Duenas, M.J. Bleda / Parkinsonism and Related Disorders 11 (2005) 387–392 391

twelve months of the event), impairment is significant,

which persists over the 60-month follow-up carried out.

We believe this impairment is not the only consequence

of cognitive impairment but rather the direct cause of

delirium that would behave as a process, while the UPDRS

motor section may be influenced by dementia-associated

concurrent morbidity [29]. When the same factors of

previous Cox’s model were included, but only with patients

of PDG and PG groups, this analysis did not found that the

basal disease level (measured by H and Y) or the years of

disease become elements of risk; only the basal punctuation

of UPDRS(m) %17 become it. The involved motor degree

also has been considered as risk factor to develop dementia

[28], as delirium [6].

In that way, motor impairment measured by the

UPDRS(m) and the low STMS scores are present as

elements to increase mortality. A base line score O17,

implying increased motor involvement, was in our patients a

mortality risk factor.

Delirium is acute by definition [7] and it was mentioned

above that the dopaminergic mesocortical system is

involved in its physiopathology, which would become

hyperfunctioning [5]. But if it is considered to predispose or

start a demential picture, it should be assumed that delirium

stops being an event to become a process, and acting as such

it would condition an aberrant cerebral reparation or

become a marker of the physical frailty notion [6].

It is necessary to clarify whether these notions may be

applied to Parkinson’s disease, i.e. if delirium promoted an

aberrant neurological regeneration involving the striatoni-

gral circuitry and caused a greater affectation of the same,

patients with Parkinson’s without delirium would have a

more favourable evolution in both cognitive impairment and

mortality.

Finally, this study show the fact that delirium is a risk

factor for dementia and death for patients with Parkinson’s

disease; thus, preventing its appearance should be intended

particularly in subjects with planned elective surgeries;

Golden et al. [9] state a relative risk between 2.8 and 8.1 for

these patients to develop delirium, thus, we must insist on

the need for an early diagnosis [30].

On the other hand there is a need for relying on

harmonized diagnosis criteria so that we are able to be fully

aware of the prevalence of this major complication as well

as extrapolate results from the various studies on delirium

available.

5. Conclusions

Delirium is a syndrome that should be prevented,

particularly in patients likely to develop it such as

Parkinson’s patients. Delirium is per se a risk factor to

develop dementia and motor impairment. Both, cognitive

and motor impairment, in turn interact with and potentate

each other influencing finally in an early mortality.

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